Centrifugal separator



H. R. DRURY 2 Sheets-Sheet 1 S I Z n I n s 22 65 4 \gg /7 A9 .37

INVENTOR.

NUV m W54 H. R. DRIURY 2,695,333

CENTRIFUGAL SEPARATOR Filed Aug. 26, 1953 2 Sheets-Sheet 2 United States l atetnr' 2,695,133 CENTRIFUGAL SEPARATOR Herbert R. Drury, Corona del Mar, Calif.

Application August 26, 1953, Serial No. 376,661

9 Claims. ((31. 233-2 This invention relates to centrifugal "separating devices and more particularly 'to sepz't'rati'ng ap aratus for classifying or separating substances containing preeious or valuable metals or other valuable mineral containing substances and to such apparatus employing a rotating bowl for imparting centrifugal action to the material under treatment.

Heretofore, in separating precious "metals, particularly gold, from alluvium or gangue, placer gravels and sand or mine residue in which it is found, there has always been a considerable amount of black sand present as an undesirable element. The presence 'of black sand had presented a problem in gold separation as it interfered with the separation process, clogging the separating equipment and was therefore discarded as a nuisance.

Owing to recent discoveries that black sand contained valuable mineral substances such as ilmenite, chromite, thorium and magnetite, there is a growing demand for such black sand in reasonably clean concentration, particularly from the gravels and sands-obtained from the rivers and beaches of California and Oregon. It has been determined that the black sands in these areas contain one pound uranium thorite in every ton. This mineral "substance has a seven percent concentration of uranium oxide and a seventy percent concentration of thorium. Although the black sand can be separated from the gray sands or gravels by electromagnetic treatment, such process is comparatively expensive due to the fact that the sands or gravel must be baked to absolute dryness before being treated electrically.

By the present invention, there is provided a 'rnethod and apparatus therefor, for treating sands, gangue, gravel and the like, containing precious metals and black sand which overcomes the difliculties present in prior practices which serves to effectively separately classify and recover precious metals and black sand in a single operation. Accordingly, it is among the objects of my invention to provide centrifugal concentrating apparatus whereby valuable metals and black sand may be efficiently and economically separated from alluvium or gan'gue, ,pl'aeer gravel and sand or mine residue. A further object of the invention is to provide centrifugal concentrating apparatus for treating material to separately recover precious metals and black sand wherein the precious metals are separated in one zone of the apparatus and the black sand in another Zone as the material under treatment passes through the apparatus.

These and other objects and advantageous features of the invention not at this time more particularly pointed out will become more apparent as the nature of the invention is better understood from the following detailed description taken in conjunction with the accompanying drawings wherein like reference characters denote corresponding parts, and wherein:

Figure 1 is a fragmentary top plan view of a centrifugal separating device embodying the :present invention,

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1 with parts broken away and omitted,

Figure 3 is an enlarged sectional detail of the preferred type of liner constructionfor the device,

Figure 4 is an enlarged sectional detail view of a modified form of liner construction, 7 p

Figure 5 is an enlarged sectional detail of a further modified form of liner construction,

Figure 6 -is anenlarged perspective detail of the im- 2,695,133 Patented Nov. 23, 1954 pellet and riffie construction disposed at the lower p'ornon of the side wallet the liner for the bowl, and

Figure 7 is a side elevational view of reduced scale of the device .of the invention with parts thereof broken away and in section.

With reference to the accompanying drawings, there is illustrated a centrifugal separating device constructed in accordance with the teachings of the present invention and comprising a base or supporting frame 10 ineluding opposed side frame members 11 and 12, the adjacent ends of which are mitered and welded together to term a rectangular base fr'ame. Extending between the side frame members 11 (see Figure 7) are a pair of spaced angle irons 13 upon which is centrally positioned a supporting plate 14. Mounted on the plate 14 and secured to theangle irons 13 is an upstanding journal box 15 formed with an internal axial bore 16. p

The journal box 15 supports in the bore 16 thereof a vertica11y d-isposed Shaft 18 rot-atabl-y mounted in a thrust bearing -1-'/ which is supported on the upper surface of the journal box 15. Keyed to the shaft 18 above the bearing 17 is a sheave 19 which is connected to a suitable source of power for rotating the shaft 18 as will be described hereinafter. The upper end of the shaft 18 extends into the bore 20 of a depending hub 21 formed on the lower surface of a supporting disk 22 and is maintained therein by means of set screws 23 (see Figure 2). Mounted on the upper surface of the disk 22 is a frustro-conical concentrating bowl 24 which may be made of any suitable material such as aluminum, iron, steel, plastic or molded hard rubber if desired. The bowl 24 is secured to the disk 22 for rotation therewith by means of suitable bolts 25.

The apparatus for rotating the bowl 24 and the supporting structure therefore is best illustrated in Figure 7 of the drawings and includes a motor 26 mounted on a plate 27 supported between spaced angle members 28 secured to the frame 10. Although an electric motor is illustrated in the drawing, any other suitable power means may be employed depending upon the particular site where the separating bowl is to be set up and used. Extending parallel to the drive shaft 29 of the motor is a cou'ntershaft 30 suitably supported in spaced brackets 31 and 32also mounted on the frame 10. A pulley belt 33 operatively connects pulley 34 keyed to the end of the countersha'ft 30, to pulley 35 on the motor shaft 29. Mounted on the coun'tershaft 30 is a sheave 36 which is aligned with and arranged to drive the sheave 19 of the bowl supporting assembly through a belt 37. V

The bowl 24 is preferably frustro-conical in configuration being formed with a smooth interior surface, with the base thereof resting on the upper surface of the disk 22 and being secured thereto by the bolts 25. The side wall of the bowl may extend at an angle of between fifty and sixty degrees to the plane of the base, however, it has been found that if the pitch of the side wall is approximately fifty-eight degrees with respect to the base, the material introduced into the bowl is properly worked as it passes upwardly along the side wall of the bowl "and maximum separation is obtained before it is discharged from 'the bowl. Furthermore, maximum speed of operation and capacity is obtained with the aforesaid angulation of the side wall. Spaced from the upper edge of the bowl and extending circurnferentially about the side wall of the bowl is a plurality of narrow elongated openings or slots 38. Between each pair 'of slots 38 there is securedto the inner surface of the bowl a flow strip 39 extending 'from'th'e slots 38 downwardly into the bowl. The function of the flow strips and slots will beoome more apparent from the description hereinafter. v Mounted in the bowl 24 so as to substantially cover the entire inner wall surface thereof is a frustro-conical litter or basket 40. The basket 40 includes a base plate 41 arranged to be secured to the bottom of the bowl by means of removable bolts 45, a rigid ring 42 of sufficient diameter to seat within the open end of the bowl and a second ring 43 of a diameter sufficient to permit seatinginterrnediate the ring 42' and the base member 41. Extending between the plated! and ring 43fan'd preferably welded to each is a wall portion "44 I which is suitably formed of wire mesh, or expanded metal lath (Figure 4). Disposed between the wire mesh wall portion 44 and the interior wall of the bowl is a covering 46 made of a suitable fabric material such as burlap or blanket material. This covering serves to entrap and hold the particles of precious metal separated from the material treated in the lower portion of the bowl. The wall portion 48 of the basket 40 between the ring members 42 and 43 is constructed of an outer layer of wire mesh 49 and an inner layer of fine mesh wire screening or filter material 50. The wall portion 48 of the basket is maintained in spaced relation to the inner wall surface of the bowl by means of the spaced metal fiow strips 39 which extend in an axial direction and are secured to the wall in any suitable manner. The strips 39 serve to space the fine wire mesh from the inner surface of the wall and thereby define a passageway therebetween which terminates in the slots 38.

Mounted in the bottom of the basket 40 adjacent to the intersection of the side wall portion 44 thereof and the base plate 41 is a rifile ring 53 suitably welded to the wall portion 44 at a point vertically spaced from the base plate 41. Spaced diametrically with respect to the outer rifile ring 53 is an inner riffie ring 54 which is connected to the outer ring by means of a plurality of tie members 55. A series of perforated plate segments 56 are supported by the frame formed by the inner and outer rifile rings. Extending between the inner riffie ring 54 and the base plate of the basket and serving to support the former in spaced relation to the latter are a plurality of vertically extending finger members 57, each of which is arranged to support an impeller plate 58. The impeller plates are preferably mounted at an angle of forty-five degrees to the members 57 and have their inner edge surface spaced from the wall portion of the basket and extending parallel thereto.

A circular launder 60 is coaxially positioned about the rim of the discharge edge of the bowl. The launder 60 includes an outer cylindrical wall 61, an inner cylindrical wall 62 and a fiat inclined bottom 63, thus forming an asymmetrical annular chamber. A rectangular discharge chute 64 is provided adjacent the lower portion of the bottom 63. The walls, bottom and chute are suitably secured together as by welding to form a complete unit. Spaced from the wall 62 and supported therefrom is a wall member 65 which together with a bottom wall 66 connecting the bottom of the wall 65 to the wall 62 defines an auxiliary launder 67 which serves to collect material discharged from the bowl 24 through the slots 38 in the wall thereof. The launder 60 and auxiliary launder 67 connected thereto are supported by a plurality of angle brackets 68 bolted or otherwise secured to upright frame members 69 mounted on the base 10.

The bowl 24 receives material to be separated or classified from a feed chute 70 which opens into the interior of the bowl adjacent the bottom thereof. A suitable bracket 71 (Figure 1) extending from the upright members 69 serves to maintain the chute in proper operating position within the bowl.

With reference to Figure there is illustrated a modified construction for the upper portion of the basket. In lieu of the wire mesh 49 and wire cloth 5 I provide a perforated wall 72 which is supported on the flow strips 39. Disposed on the wall 72 is filter skin 73 which may be made of plastic or other suitable material. Superimposed on the filter skin is a perforated wall member 74 preferably made of stainless steel and serving to protect the filter skin and allow the accumulation of coarse sand on the skin to be washed away and fine material such as black sand to penetrate the filter skin freely.

In using the separating bowl of the present invention the gangue or conglomeration containing precious metallic substances and black sand mixed with sufiicient Water to carry it is introduced into the bowl 24 through the feed chute 70 and deposited in the bottom of the bowl which is being rapidly rotated. I have found that where a bowl with a diameter of thirty-six inches is used a speed of about two hundred R. P. M. is preferable. The rapid rotation of the bowl creates a centrifugal force which moves the material radially outwardly along the bottom of the basket where it engages the impellers 58 which agitates and breaks up the flow. The turbulence in the flow of material caused by the impellers 58 segregates the fine material from the coarser particles, the former passing through the perforated riffle plate 56 and the latter being forced to pass outwardly around the plate leaving the gold nuggets disposed under the riflle.

The fine material which has passed through the riflle plate is worked against the wire mesh 44 as it moves upwardly along the wall of the basket. The mesh causes the material to separate and the heavier particles of gold to pass through the mesh and become entrapped by the fabric liner disposed therebeneath. The black sand being heavier than the remaining material will pass through the mesh but being lighter than the gold does not prevent the latter from working itself into the fabric where it is retained. The remaining material including the black sand moves upwardly along the wall of the basket to that portion above the ring 43. In this section the finer particles including the black sand are worked by the wire mesh 49 against the wire mesh cloth 50. The mesh cloth is such that the black sand will pass therethrough but the balance is excluded. The black sand passes upwardly along the wall of the bowl through the passage defined by the flow strips and the wire cloth and is directed into and through the slots 38 where it is received in the auxiliary launder 67 from which it passes to a suitable place of storage not shown. The balance of the material under treatment passes outwardly over the peripheral edge of the bowl into the launder 60 and is directed to a suitable place of disposal by the discharge chute 64. This action continues until the fabric liner 46 has become fairly well saturated with gold or other precious metal at which time the feed of solid material into the bowl is first cut off and then rotation of the bowl is stopped. The bolts 45 are removed and the water is permitted to drain out of the bowl into suitable receptacles. The wire basket is removed from the bowl after which the fabric liner or bag is carefully washed to remove therefrom the gold or other precious metal particles which have become entrapped therein. After the bag and basket have been replaced in the bowl the device is ready to continue the separating operation.

Having thus described my invention so that those skilled in the art may practice the same, what I desire to obtain by Letters Patent is defined in the appended claims.

I claim:

1. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustroconical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl, a ring member arranged to engage within the peripheral edge of the bowl, and a second ring engageable with the wall of the bowl intermediate the base and said first ring, open mesh material spanning the space between said rings and said base plate, fabric material disposed adjacent to the wall of bowl between said second ring and the base plate, and wire cloth disposed between the bowl wall and the open mesh material between said first and second rings.

2. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl, a ring member arranged to engage within the peripheral edge of the bowl, and a second ring engageable with the wall of the bowl. intermediate the base and said first ring, open mesh material spanning the space between said rings and said base plate, said side wall having a ring of spaced slots formed adjacent said first ring, fabric material disposed adjacent to the wall of bowl between said second ring and the base plate, wire cloth disposed between the bowl wall and the open mesh material between said first and second rings, and a plurality of elements secured to the wall and serving to maintain the wire cloth spaced from the inner surface of said bowl wall.

3. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein. said basket including a base plate arranged to seat on the base of the bowl, a ring member arranged to engage within the peripheral edge of the bowl, and a second ring engageable with the wall of the bowl intermediate the base and said first ring, open mesh material spanning the space between said rings and said base plate and a rifiie ring including a plurality of impellers mounted adjacent the intersection between the mesh material and the base plate.

4. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base oi the bowl, a ring member arranged to engage within the peripheral edge or the bowl, and a second ring engageable with the wall of the bowl intermediate the base and said first ring, open mesh material spanning the space between said rings and said base plate, fabric material disposed adjacent to the wall of bowl between said second ring and the base plate, wire cloth disposed between the bowl wall and the open mesh mate rial between said first and second rings and a rifile member mounted adjacent the joint between the mesh material and said base plate.

5. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl and an open mesh side wall, fabric material positioned between the lower portion of said mesh side wall and the wall of the bowl, and a filter element positioned between the upper portion of said mesh side wall and the wall of the bowl.

6. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl and an open mesh side wall, fabric material positioned between the lower portion of said mesh side wall and the wall of the bowl, a filter element positioned between the upper portion of said mesh side wall and the wall of the bowl and spaced from the latter, and means for directing material passing through said filter into a place of storage.

7. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl and an open mesh side wall, fabric material positioned between the lower portion of said mesh side wall and the wall of the bowl, a filter element positioned between the upper portion of said mesh side wall and the wall of the bowl and spaced from the latter, and rifile means mounted on said base plate adjacent the side wall of the basket.

8. A centrifugal separator comprising a frustro-conical bowl for receiving materials to be treated including a base and a side wall having a plurality of circumferentially arranged openings spaced from the peripheral edge thereof, means for rotating said bowl at high speed, a removable frustro-conical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl and an open mesh side wall, fabric material positioned between the lower portion of said mesh side wall and the wall or" the bowl, adapted to receive heavy particles separated from the material in the lower portion of the bowl, and filter material positioned between the upper portion of said mesh side wall and means for directing material passing through said filter material into the openings in the side wall of the bowl.

9. A centrifugal separator comprising a frustro-conical bowl for receiving materials to'be treated including a base and a side wall having a plurality of slots arranged circumferentially adjacent the upper edge thereof, means for rotating said bowl at high speed, a removable frustroconical basket complemental to the inner surface of the bowl and adapted to be received therein, said basket including a base plate arranged to seat on the base of the bowl and an open mesh side wall, a ring member separating said side wall into upper and lower portions, fabric material positioned between the lower portion of said mesh side wall and the wall of the bowl, a filter element positioned between the upper portion of said mesh side wall and the wall of the bowl and spaced from the latter, and means for maintaining said filter element spaced from the wall of the bowl, said means and filter element defining a passageway through which material passing through said filter element is directed into said slots.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 764,197 Muhleman July 5, 1904 942,663 Rachelman Dec. 7, 1909 1,385,724 Smith et al. July 26, 1921 1,581,089 Roberts Apr. 13, 1926 

